The present invention relates to a safety device for a double-circuit type air brake system for a vehicle, wherein even when one circuit is damaged or trouble occurs therein the other circuit of the air brake system can continue to normally operate.
It is generally provided in a vehicle air brake system to reserve compressed air, produced in one compressor, in a pair of independent air reservoirs, and to actuate a double-circuit air brake system from the pressure source of the pair of air reservoirs. Such a pair of air reservoirs are usually of sufficient size for reserving compressed air needed for braking operations a few times in succession. Even when one circuit of the two gets into trouble (or is damaged), i.e., becomes incapable of braking operation due to insufficient air pressure, the other side circuit can still continue to work for braking the vehicle a few times to halt the same. It has been very effective in fact in enhancing the safety of a moving vehicle.
In such a conventional air brake system, the compressed air supplied from the compressor, in case of a damage in any one circuit, will leak out largely from the damaged portion of the disabled circuit, causing the other normal side circuit to be incorrectly supplied with compressed air, which results in speedy exhaust thereof and finally in a complete failure of brake operation.
For avoiding such a trouble, installation of a pressure gage in the brake circuit was commonly practiced to warn the driver of pressure falling below a predetermined value, and mounting of a warning lamp to alert the driver of the trouble was another way. The driver could repair the damaged portion or close a cock for air supplying in the damaged side circuit, upon once stopping the vehicle. A negligence (or overlooking) in watching the pressure gage or warning lamp, by any chance, would cause the driver to miss the timing of the repair or emergency countermeasure, leading to a critical danger.